KDebug Debug Features

[Clownacy]

This is something that Vladikcomper has brought up a few times: Gens KMod and BlastEm support the KDebug API, which allows emulated software to call into the emulator for a handful of uses, such as debug logging. On a real Mega Drive, using this API is harmless since it is done by accessing unused VDP registers. Though, I wonder about buggy games and homebrew that just access these registers accidentally: the last thing I need is to try to print garbage data as a zero-terminated string.

Some documentation can be found here: https://github.com/vladikcomper/md-modules/blob/master/modules/errorhandler/docs/how-to/Use_KDebug_integration.md